# How Does Thermodynamics Explain Work Done in Biological Systems?

• TytoAlba95
In summary, work is done on a biological system when the system does mechanical work on something else.
TytoAlba95
What is meant by work done by the system and work done on the system, in biological systems?

In physics related systems however:
Work is simply a force multiplied by the distance moved in the direction of the force. A good example of a thermodynamic system that can do work is the gas confined by a piston in a cylinder. If the gas is heated, it will expand and push the piston up, thereby doing work on the piston. If the piston is pushed down, on the other hand, the piston does work on the gas and the gas does negative work on the piston. This is an example of how work is done by a thermodynamic system.

SanjuktaGhosh said:
What is meant by work done by the system and work done on the system, in biological systems?

In physics related systems however:
Work is simply a force multiplied by the distance moved in the direction of the force. A good example of a thermodynamic system that can do work is the gas confined by a piston in a cylinder. If the gas is heated, it will expand and push the piston up, thereby doing work on the piston. If the piston is pushed down, on the other hand, the piston does work on the gas and the gas does negative work on the piston. This is an example of how work is done by a thermodynamic system.
In thermodynamics work (W) is macroscopic mechanical work performed by a system of molecules in moving between states of thermodynamic equilibrium. It is not difficult to find examples of biological systems doing work. It is a bit more difficult to provide examples of work being done on such systems. Living systems are essentially heat engines to do macroscopic mechanical work.

A biological system doing work: The human body can mechanically lift a weight for example. The muscle movement required to lift a weight is the result of thermodynamic processes taking place in muscle cells that convert internal (chemical) energy into heat flow. The human heart can be thought of as a thermodynamic system that uses internal (chemical) energy in its cells to create heat flow that causes the heart muscle to contract and expand, pumping blood through the body.

Doing work on a biological system: By applying CPR to a stopped human heart, one does work on that system and causes the heart to pump blood.

AM

TytoAlba95
Sorry for the late response. So basically for biological systems work is being done by the system and rarely on the system.

I would not say "rarely", because work is being done on biological systems all the time. For example, when a mammal infant draws milk from its mother it is doing work on a biological system; or when a python squeezes its prey; or when air currents lift a bird; or when a wind gust breaks a tree branch; or when a tree root pushes soil to grow roots (the soil being a sort of biological system); etc.

AM

Last edited:
TytoAlba95

## What is thermodynamics in biology?

Thermodynamics in biology is the study of how energy is transferred and transformed in living organisms. It focuses on the principles and laws of thermodynamics as they apply to biological systems.

## Why is thermodynamics important in biology?

Thermodynamics is important in biology because it helps us understand how living organisms use and manage energy. It also explains how organisms maintain their structure and function, and how they respond to changes in their environment.

## What are the laws of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted from one form to another. The second law of thermodynamics states that in any energy transfer or transformation, some energy will be lost as heat.

## How does thermodynamics relate to metabolism?

Metabolism is the set of chemical reactions that occur in living organisms to maintain life. These reactions involve the transfer and transformation of energy, making thermodynamics a fundamental concept in understanding metabolism.

## What are some real-world applications of thermodynamics in biology?

Some real-world applications of thermodynamics in biology include understanding how plants convert sunlight into chemical energy through photosynthesis, how animals use energy from food to perform work and maintain body temperature, and how temperature and energy availability affect the distribution and abundance of species in ecosystems.

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